For the experts out there... How much knock retard under power does it take to 'feel something'? I just bought a 2019 CT6 3.0TT that I strongly suspect was filled with 87, while it requires 93. I haven't worked through that tank yet (getting there), and of course when I get it down to fumes, I'm going to fill it with 93 like it's supposed to get and I suspect the issue will go away, but I've noticed a 'shuddering' under load, and when I set up some PIDs to log with my V2 and did so, and marked the logging when I felt it, when I reviewed the logs, there was knock retard where I marked the log when I felt 'something'. It was only about 3*, which doesn't seem like much, but it was there. Is 3* of KR actually enough to 'feel something'?